Although dioxanes have been widely used as solvents for various chemicals and are generally present as impurities in certain surfactants, such as alcohol and alkyl phenol ethoxylates and derivatives thereof, such as sulfate, sulfonate and phosphate esters, recent evidence of animal carcinogenic and other harmful properties has discouraged their unencumbered utilization. Accordingly, when plants, or animals are exposed to products containing polyoxyethylene compounds, the dioxane impurity must be significantly reduced to very low levels, preferably less than about 5 ppm. When a small amount of the dioxane impurity is present in pharmaceutical or cosmetic formulations, even more stringent purification is desired for its removal below the current detection limit of about 0.5 ppm.
Small quantities of dioxane are also formed in the reaction of ethylene oxide with an acitve hydrogen atom containing compound such as an alkylphenol, mercaptan, amine, acid, etc. to produce ethoxylated products which find widespread application as emulsifiers, dispersants and foaming agents. Objectionable amounts of dioxane from these sources are often present in these final products, thus presenting a potential health hazard.
Several processes for the removal of this troublesome contaminant from products of manufacture have been proposed, namely sparging alkoxylated products, e.g. ethoxylated compounds, with nitrogen, air or steam; however, such methods have not resulted in adequate removal of the contaminant from waste gases to insure safe exposure and venting of the waste gas, containing the dioxane to the atmosphere, remains a serious problem.
Accordingly, the present process is directed to removal of dioxane from effluent waste gases for safe release of the treated gas to the atmosphere and to containment of the dioxane in a concentrated state for reduced volume storage or safer disposal by incineration, chemical conversion or by other suitable means.
Hence, it is an object of the present invention to remove dioxane from various waste gases to a level such that the gases may be safely vented to the atmosphere and to provide an economical and efficient process for accomplishment of this purpose.
Another object is to provide a process for recovering dioxane from waste gases in a substantially non-volatile and concentrated, chemically complexed form.
Still another object of this invention is to provide a process for removing dioxane from waste gases to less than 0.5 ppm before venting to the atmosphere.
These and other objects will become apparent from the following description and disclosure.